Down is the best thing to keep you warm but is crap when wet so for winter either get a down bag with a good highly water resistant outer fabric or just stick to a synthetic bag. Synthetic bags tend to be a lot more bulky though especially with a winter rating, say -5C
Ton you're more than likely going to have to get a Long or XL version. Most US manufacturers std length is only 6ft so you'll need a long version e.g. TNF, Mountain Hardwear, Marmot
Even for UK makes like Mountain Equipment you'll need the XL cos you're a big lad.
There are loads of threads on here about sleeping bags and the relative merits of down & synthetic bags.
Golden Rule of bivvying is don't fully zip/close it up as the condensation will make it miserable inside

druidh - Member
For bivvying, I'd avoid down and go for something like a Mountain Hardware Lamina 0

Ton - these are great synthetic bags but you will deffo need the XL but you'll also need to try before you buy to see if it's wide enough at the chest. GoOutdoors in Stanningley stock the Lamina range so pop in to see if they've got what you need

Ton, you signing up for 'El & Back? Do you have a bivy bag already? If it's nice & breathable, I'd stick with a down sleeping bag imho (or quilt). Whether the bag/quilt gets wet will depend more on where you pitch than anything else.

XL Hunka was my first bivy bag, a good'un for the price. You'll have lots of space in there for a winter bag to loft. Don't forget you'll need a warm mat...even with a warm bag you'll get very cold if your mat isn't up to the temp. Got a tarp?

On this year's January equivalent to the El & Back (called Mach n Back) it was well frosty and sub zero in the night. However, some of us slept amongst the conifers where the temperature stayed nicely above zero and we weren't coated with frost and condensation upon waking in the morning

BTW, could any late arriving riders chosing to kip down in the same vicinity as us on The El 'n Back please keep the noise and lumens down as you stagger up from the pub in the early hours? Cheers.

All depends on conditions and picking a good spot, as to how cold you can be and still be comfortable.

Things to think about is how warm do you sleep?
Is it better to get a good 3 season bag which you will use more and then layer up? Coat, liner, thermals, hat & socks etc.
A good mat is as important as a good bag.

Don't know how the other more serious camping/bivying types rate them but I find a silk liner invaluable. My girlfriend is always sleeps cold, on our last camping weekend it got pretty frosty over night but in her 3 season bag and a silk liner she slept like a baby.

Look for R ratings the higher the better. You'll loose more heat via the ground than via the air.

Love my neoair. Exped and Peak Elite also get good recomendations (but all on the higher end price wise)
Foam mats work just as well, cheap but bulky. Many options available. Tried short mats, but after using a long mat, theres no going back for me.

Alpkit stuff is brill for bivvies and mats.
Ton, have a pop into go outdoors at pudsey or wakefeild as they have a good selection of bags.
For me a nice down one is always preffered. Have Rab and alpkit ones, all good.